The C2N surface as a highly selective sensor for the detection of nitrogen iodide from a mixture of NX3 (X = Cl, Br, I) explosives

Abstract

Explosives are quite toxic and destructive; therefore, it is necessary to not only detect them but also remove them. The adsorption behavior of NX₃ analytes (NCl₃, NBr₃ and NI₃) over the microporous C₂N surface was evaluated by DFT calculations. The nature of interactions between NX₃ and C₂N was characterized by adsorption energy, NCI, QTAIM, SAPT0, NBO, EDD and FMO analysis. The interaction energies of NX₃ with C₂N are in the range of −10.85 to −16.31 kcal mol⁻¹ and follow the order of NCl₃@C₂N > NBr₃@C₂N > NI₃@C₂N, respectively. The 3D isosurfaces and 2D-RGD graph of NCI analysis qualitatively confirmed the existence of halogen bonding interactions among the studied systems. Halogen bonding was quantified by SAPT0 component energy analysis. The SAPT0 results revealed that ΔE_disp (56.75%) is the dominant contributor towards interaction energy, whereas contributions from ΔE_elst and ΔE_ind are 29.41% and 14.34%, respectively. The QTAIM analysis also confirmed the presence of halogen bonding between atoms of NX₃ and C₂N surface. EDD analysis also validated NCI, QTAIM and NBO analysis. FMO analysis revealed that the adsorption of NI₃ on the C₂N surface caused the highest change in the E_HOMO–LUMO gap (from 5.71 to 4.15 eV), and resulted in high sensitivity and selectivity of the C₂N surface towards NI₃, as compared to other analytes. It is worth mentioning that in all complexes, a significant difference in the E_HOMO–LUMO gap was seen when electronic transitions occurred from the analyte to the C₂N surface.